Bit shifting and bitwise and:

my $hex    = hex("1c023d64");
my $mask   = 31 << 5;
my $result = ($hex & $mask) >> 5;

printf "Hex:    %30b\n", $hex;
printf "Mask:   %30b\n", $mask;
printf "Result: %30b (%d)\n", $result, $result;
[download]

shows the result like this:

Hex:     11100000000100011110101100100
Mask:                       1111100000
Result:                           1011 (11)
[download]